Venus cloud formation in the meridional circulation
Venus cloud formation in the meridional circulation
复制标题
经向环流中金星云的形成
DOI：
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
G. Hashimoto
中科院分区：
文献类型：
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作者：
T. Imamura;G. Hashimoto
二维模型研究表明，经向环流对金星云和可冷凝气体的分布有很大的影响。在我们的模式中，由于低纬度和高纬度云层厚度的增强，再现了中纬度地区普遍观测到的近红外光学厚度下降。在高纬度地区，模拟的上层大气中H2SO4-H2O液滴的极向输送形成了厚云，这是因为光化学生成的H2SO4-H2O液滴大部分通过经向环流向极输送。在低纬度地区，模拟的高浓度H2SO4蒸汽的大尺度上升形成了致密的低层云，这与进入探测器的观测结果一致。模拟的经向环流使H2SO4水汽在云下向赤道方向输送，以及低层云中液滴的沉降导致低纬度云底周围H2SO4水汽的积累。计算得到的H2SO4蒸汽分布与射电掩星观测结果一致。中间云似乎是由对流混合从下方向上输送的H2SO4蒸汽凝结形成的。
A two-dimensional model study revealed that the meridional circulation can have a large influence on the distributions of the cloud and condensable gases on Venus. In our model, the generally observed depression of near-infrared optical thickness at midlatitude is reproduced as a result of the enhancement of cloud thickness at low and high latitudes. At high latitudes, the modeled poleward transport of H2SO4-H2O droplets in the upper atmosphere makes a thick cloud, since most of the H2SO4-H2O droplets photochemically produced are transported poleward by the meridional circulation. At low latitudes, the modeled large-scale ascent of the concentrated H2SO4 vapor forms a dense lower cloud in accord with observations by entry probes. The equatorward transport of H2SO4 vapor below the cloud by the modeled meridional circulation and the sedimentation of droplets in the lower cloud leads to the accumulation of H2SO4 vapor around the cloud base at low latitudes. The calculated H2SO4 vapor distribution agrees with radio occultation observations. The middle cloud appears to be caused by the condensation of H2SO4 vapor transported upward from below by convective mixing.